Method of preparing guanamines



Patented Jan. 18, 1949 a l $459,710

A UNITED STATES ICE" LIETHOD F PREPARING GUANAMINES J ohnstone S. Mackay, 01d Greenwich, am} Joseph H. Parlen, Stamford, Conn., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing; Application July 9,; 1946, Serial No. 682,284

7 Claims (Cl. 260-2495) The present inrention relates tothe Dreparato the guanamines may be written, empirically, tion of guanamines oft'he formula a as fqllowsz: r

. a I .7 R

1N1. N 1 I, Hm %,NFH2 N .v

t I R where R. is hydrogen, or any aliphatic or are- I to matiohydrocarbon radical; 1 I, Z y a 2M I-Ieretofore, guanamines have beenprepared by T 1- RON 3NH-a+2 O Q1,- reacting biguanideswith esters, acid chlorides or Q ,TN 1 7 acid anhydrides, by reacting dieyancliamide with in 4 N I amidine salts or nitril'es, and: by the pyrolysis of uanidine salts of organic acids In view of the However the formatwnofthe euanammes o expense of the'bigua'nides, amidine" salts, nitri-les guamdes' a ammonia Probably f Place and: guanidine aIts-it isreadily apparent: that the zggg g 35 21 1 i if reactions raglgr itarzlilng 1113158115 18 enployect 1n=-al=l thse llel7htigs 2Q p i gt th: gsriagiggnvaitfivieile 1133s or eaprepara ion- 0 guanam-mes are su cieny expensive to render the-production of the desired: F32? g wuchlreactlon fit uanamineshlikeriivise eXpan's'ig e-l 0n tltilef Otilfilf k g jfiifs ifg fi g er i3 igg gg a hand a met 0d asrecen -y een devise 1 or Y e production of guanicles whereby di' lzlyandiam-ide is g gigg i g iiggggigg 23%;: gg gz acid. topreparean acyl carbamylguanidine which $2 33? il g 2 g fie, cagloonl d1oxrilc ile-arlild may be .thereaftqr cycnzed to g d treatabo i l e 31131311 552; that ghe a nfm 'iia em ggiig ffiz gfiga ggi fiigfig j mmammoniation of the. hydroxy triaz-ine; ammeline, y a V ,1" the; guanidesdo. not; exhibit. any. marked tendency R L 35 todecomposeand provideammoniajso thatiit is, l a 1 so-farlas maybe determined, impossible tosimply heatguani'des; in aselosed vesselilandi obtain any i v 5 guanamine. The presence or'ammonia must be m E vv v provided if any conversion of guani'de to g'uane \N? 7 mime is t0 be. 0btaine d-.. 1 Further; it has: been a t ,q ound; that. ammoniajexertsna;.stabilizinginflue where R, may be hydrogen, or any aromatic or ence on guanamine'ssand since" it also-tends to aliphatic radical. Obviously, if suoh guanides; favor he reaction lay-virtue: of mass actione'emcould be converted. to the corresponding: guan; I siderations a largeexcess -or ammoniai reatly amines by inexpensive meansa cheap-sourc q excesslof that; required by-"the above equation has guana-mines would be provided. 7 i een found to be beneficial.

h as nqw. been discovered th-at guana mjngs; While the reaction maybe carried out? over' a can be prepared by heating the'aforementionecl Wide range of temperatures, an additionalpoint guanides in the presence of ammqniaat t emr of difference between the" ammoniati'on of cyan- Deratures withinlthe; range or; substantially 250- uric acid, ammelide, and. ammeline to yield mel- 0 C, thusproviding an inexpensive meansof amine and'theammoniation e1 guanides to yield converting guaiz ides to guanamines; and aecordguanamines resides in the" deleterious effect of ingly-jmaking suchguanaminesv available at; low excessivel high" temperatures on the yieldsvof 1; v v V l 4 guanamine-providedi. This is indicated by the The equation for the conversion of the guanilies data: of: vTable i shown hereinafter. Said data Table I Tempera- Guanamine mm Yield. H 0. Hours Per cent From the above data it is apparent that optimum yields are provided at a temperature within the range of substantially 325-375 C. while lower yields are obtained at either 300 C. or 400 C. Appreciable yields are alsoobtained by carrying out the reaction at temperatures of 250 and 500 0., although, as is obvious, they are considerably less than those provided by operating within the narrower range of 300-400 C.

To determine the optimum ratio of reactants a series of experiments was carried out by reacting varying amounts of benzoguanide and ammonia at 350 C. for 2 hours using an autoclave having an internal capacity of 300 cc. and otherwise. theesame technique as, above described. The','averaged data'obtainedin this series of runs are shown in Table II below: 3 t

Tabled! Ben zogua- NHa Guanamine nide v Yield Grams ,Grams Per cent 35 p so 4 so 25 51 75 25 I a '30 tion a practical medium'would be. struck and capacityof 1 production would not be sacrificed for the sole purpose. of'obtaining' higher percentageyi'elds. While :there is no very close correlation between the. amountof" ammonia employed in the reaction," as expressed in terms of its partialpressure, and, as indicated herein-' above, reaction may be expected to occur so long as the presence of ammonia is provided, nevertheless, it is preferred that a minimum of about 200 lbs/sq. in. of ammonia pressure be provided. Maximum yields are obtainedat ammonia pressures of substantially 2000 lbs/sq. in. and above. Although pressures considerably above 2000 lbs./sq.in. may be employed if desired, such additionally high'ammonia pressures serve to provide no additional advantage and only necessitate the use of stronger reaction vessels.

.Other guanides which have been ammoniated to the corresponding guanamines-are aceto capro-,glaura-, sebaco-L and propionog'uanide and in all cases the above discussed conditions of temperature, ratio of reactants and other conditions of reaction have been found to hold. In each of these cases the corresponding guanamine resulted except that with sebacoguanide pelargonoguanamine was fal so produced. In the case of 'such dib'asic guanides :bothth'e diand monobasic product can be expected. Sebacoguanide is a compound of the following formula 4' 55 that it is readily apparent that the pelargonoguanamine results from splitting ofi one of the triazine rings from the bridging aliphatic chain. Other dibasic guanidesiwill provide both the diandmonobasic 'guanamines'.- ;L .Ti Isolation of the guan'a'inines'inay be effected by any suitable method but generally it will be found advantageous to efiect the separation on the basis of their solubility in sulfuric acid, or,

perhaps more correctly, the solubility of their sulfates, and the insolubility of. the guanides and by-product melamine in such acid solutions. Hydrochloric acid may likewise be used as may also; dilute nitricaacid, although the :latter is less desirable because of its'dlfiicultvhandlingfchan acte'ristics. ,Other acids; -Icapable ofii forming soluble salts iwtih thev guanamines :may also be used. a After =dissolvingioutthe guanamine and separating theiinsoluble material, asby filtration; the guanamine maybe recoveredby precipitation with alkalihydroxide or other suitable. base which. will serve .to'neutralize the acid solution. in which theguanamine is dissolved. Another convenient method of separating therguanamines relies upon their. general solubility in 'dioxane, the guanides and melamine being insoluble. .Thcprocedure is'the same as that employedwhenythe guane, amines are separated-.withz'acid except that' the guanamines are :recoveredwfrom solution .by re-. movalcof the solvent, as; by distillation or evapo-' ration, and the;guanamines;are'gallowed to crys-' tallize or otherwise precipitate. at a While there :is some. indication of increase yields;- being provided .by heating for. more than 2 hours,;'say,j;for .4 or' B-hoursi'only a smalli'in-. crease in yield; is obtained by. soldoing aridthe. practice of I using; such: longer periods or. reaction is not practical from the standpoint of production. Undoubtedly, a period of reaction of less than 2 hours may be employed but if such period of reaction is unduly shortened'the yields provided will be. correspondingly lower.

Qther guanides that m'ay bereacted in accordance with the process of the present invention include those wherein the R of the aboveiven formulais ethyl, *propyl} uw1,-= isobutyl,', ,heityl; heptyl; nonyl; dodecyl, 'lauryl, allyl, vinyl; ,cycloi hexyl; benzyl; tblyL-xylyl; naphthylfandjva 1 other aromaticr'adicals' in whic ffone or' moref hydrogens of the nn'g areiepnceamysu a li pliaticradical s as ethyh propyl; butylfvinyl, allyl,

claims. Y

. stricted solely the scope ot the appended What is claimed is: 1. A method of preparing a guanamine which comprises heating a guanide of the formula where R is a member of the group consisting of hydrogen, an aliphatic hydrocarbon radical and an aromatic hydrocarbon radical, in the presence of added ammonia under pressure at a temperature within the range of substantially 250-500 C., and recovering the thus-formed guanamine.

2. A method of preparing a guanamine which comprises heating a guanide of the formula HzN-i'l o-on where R is a member of the group consisting of hydrogen, an aliphatic hydrocarbon radical and an aromatic hydrocarbon radical, in the presence of added ammonia under pressure at a temperature within the range of substantially 300-400 C., and recovering the thus-formed guanamine.

3. A method of preparing a guanamine which comprises heating a guanide of the formula where R is a member of the group consisting of hydrogen, an aliphatic hydrocarbon radical and an aromatic hydrocarbon radical with ammonia, under an ammonia pressure of at least 200 lbs./ sq. in. at a temperature within the range of substantially 300 400 C. and recovering the thusformed guanamine.

5. A method of preparing an aliphatic guanamine which comprises heating a guanide of the following formula where R is an aliphatic ammonia under an ammonia pressure of at least 200 lbs./ sq. in. at a temperature within the range of substantially sow-400 c. and recovering the thus-formed guanamine.

6. A process of preparing an aromatic guanamine which comprises heating a guanide of the following formula where R is an aromatic hydrocarbon radical with ammonia under an ammonia pressure of at least 200 lbs/sq. in. at a temperature within the range of substantially 300-400 C. and recovering the thus-formed guanamine.

7. A method of preparinga guanamine which comprises heating a guanide of the following formula where R is a member of the group consisting. of hydrogen, an aliphatic hydrocarbon radical and an aromatic hydrocarbon radical with ammonia, under an ammonia pressure of at least 2000 lbs./ sq. in. at a temperature within the range of substantially 325-375 C. and recovering the thusformed guanamine.

JOHNSTONE S. MACKAY.

JOSEPH H. PADEN.

No references cited.

hydrocarbon radical with 

